A bunch of schools - are - doing this. I know for one that Wharton is accepting applications right now for the MBA program (and without GMAT or GRE scores), so long as you plan to take one of those years by the end of August. Ditto with Cornel Law School as well as Duke, and Georgetown law. I’d Assume then that other schools are doing this as well. (It’s mainly bc international students won’t be able to start in the fall, leaving like 6-10 percent of slots unexpectedly open at schools.
FYI you will not have to wait until April 1 for Fletcher (MALD) decisions. They’re being released next week
(and it’s just a hunch but I’d be willing to bet that they’ll be out by Tuesday, or, in the case they run some hiccup, Wednesday at the very latest)
EDIT: according to someone in the Fletcher 2020 thread one of the admissions people told them that they’re aiming to decisions out on the 9th (Monday), so it might be even sooner. Good luck!